Need help with custom enum properties in Qt6 Designer

[Ivan Sinkarenko]

Hi everybody,

I've seen there's been a lot happening with enums in PyQt6,
and I've managed to adapt to most of the problems, except one.
I cannot figure out how to make custom enums work in custom widgets
that are exposed to Qt Designer.

This is my simplified code:

----------------------------------------------------------------------
import enum
from PyQt6 import QtDesigner, QtGui, QtWidgets, QtCore

class MyWidget(QtWidgets.QWidget):

     @QtCore.pyqtEnum
     class MyEnum(enum.IntEnum):
         ONE = enum.auto()
         TWO = enum.auto()

     def __init__(self, *args, **kwargs) -> None:
         super().__init__(*args, **kwargs)
         self._prop = MyWidget.MyEnum.TWO

     @QtCore.pyqtProperty(MyEnum)
     def prop(self):
         print(f'Getting property val {self._prop}')
         return self._prop

     @prop.setter
     def prop(self, new_val):
         print(f'Setting new property val {new_val}')
         self._prop = new_val

class Plugin(QtDesigner.QPyDesignerCustomWidgetPlugin):

     def name(self):
         return "MyWidget"

     def group(self):
         return "Buttons"

     def isContainer(self):
         return False

     def createWidget(self, parent):
         return MyWidget(parent)

     def icon(self):
         return QtGui.QIcon()

     def toolTip(self):
         return ""

     def whatsThis(self):
         return ""

     def includeFile(self):
         return "pyqt6_enum_designer_poc_plugin"
----------------------------------------------------------------------

I want an enum property to be displayed in the PropertySheet.
It's correctly represented by a combobox showing ONE and TWO as 
available options.

TWO is correctly selected by default. However, when in Property sheet I 
try to set it to ONE,
as soon as I click away from there, it's reset back to TWO. In fact, the 
setter does not get called,
since the message inside is never printed. (Getter message is being 
printed).

Properties do work without issues, if they have built-in types, such as 
QColor,
or even native enums, such as Qt.Orientation.

To try this code, you can save this code to 
"pyqt6_enum_designer_poc_plugin.py" and run like so:
PYQTDESIGNERPATH=$(pwd) designer

I use Qt Designer 6.6.2 and:
- PyQt6         6.6.1
- PyQt6-Qt6  6.6.2
- PyQt6-sip   13.6.0

(Also tried with PyQt6-6.5.3 PyQt6-Qt6-6.5.3, same result)

There used to be a way to make this work in PyQt5, but in PyQt6 I tried 
multiple approaches without luck.
If anybody knows the correct path, that would be very appreciated!

Thanks,
Ivan